Update docs/til/docker.md

Closes LOS-1089

docs/til/docker.md

 # Docker
 
+For more documentation, please visit https://linux.web.cern.ch/dockerimages/
+
+CERN currently builds and maintains docker images for the following suppported distributions:
+
+| Distribution | Dockerhub URL |
+|--------------|---------------|
+| cc7   | [https://hub.docker.com/r/cern/cc7-base]   |
+| alma8 | [https://hub.docker.com/r/cern/alma8-base] |
+| alma9 | [https://hub.docker.com/r/cern/alma9-base] |
+
 ## Installation on CC7
 
 ```